Pavlovian context conditioning plays a central role in fear and anxiety, stress-induced analgesia and opioid tolerance. Context-drug associations contribute to drug tolerance, drug-seeking and drug reinforcement. Stress-induced opioid analgesia typically occurs because the stressor has become associated with its context. Finally, the acquisition of context fear is regulated by opioids. Most of the knowledge about the mechanisms and processes of context conditioning come from the area of Pavlovian conditioned context fear. Component VI uses these advances to analyze context-dependent opioid tolerance. We will examine the hippocampal dependence of context-opioid associations in analgesic tolerance using both anatomical and genetic lesions. Additionally, we will determine if already acquired tolerance can be eliminated by manipulations that weaken established memories. Finally, a clear understanding of how specific endogenous opioid receptor types participate in the regulation of fear conditioning can be obtained by using knockout mice. Together, the aims of this section dissect the interactions between opioid systems, anxiety and contextual learning.